1. Field of the Invention
The subject invention relates to an air conditioning system, and more specifically, to a method of venting a refrigerant from the air conditioning system of a vehicle during a crash to mitigate leakage of the refrigerant into a cabin of the vehicle.
2. Description of the Prior Art
Air conditioning systems with directed relief valves for venting refrigerant are well known in the art. An example of such a system is disclosed in the U.S. Pat. No. 6,085,531 (the '531 patent) to Numoto et al.
The '531 patent discloses an air conditioning system utilizing a flammable refrigerant, such as propane. The system includes the standard components of a compressor, a condenser, an expansion device, and an evaporator. The system also includes a sensor to continuously monitor leakage of the refrigerant, particularly in an air space. When a leak is detected, the sensor generates a signal. A directed relief valve receives the signal and opens the valve in response to the signal to vent the refrigerant to the surrounding atmosphere.
While venting refrigerant contained within an air conditioning system after a leak is detected helps to prevent exposure to the refrigerant contained within the air conditioning system to the occupants of a vehicle, it does not prevent exposure to the refrigerant that has already leaked from the air conditioning system. In certain situations, such as a vehicle crash, the integrity of the air conditioning system can be severely compromised in an instant, causing refrigerant to leak from the air conditioning system before the refrigerant can be vented to the surrounding atmosphere. Additionally, in such situations, the directed relief system controlling the directed relief valve may become damaged entirely, thus preventing the directed relief valve from venting the refrigerant still contained within the air conditioning system. To mitigate such situations, systems for predicting leakage of a refrigerant from an air conditioning system have been implemented to vent the refrigerant from the air conditioning system before the leakage occurs. An example of such a system is disclosed in the U.S. Pat. No. 6,240,7381 (the '738 patent) to Kato et al.
The '738 patent discloses a refrigerant relief device for an air conditioning system having a sensor. When the sensor senses deceleration of the vehicle greater than a predetermined threshold amount, for example, an impact due to a collision of the vehicle, a CPU supplies current to a relief valve, discharging the refrigerant from the air conditioning system.
An additional system that predicts the occurrence of a vehicle crash is the U.S. Pat. No. 5,684,701 (the '701 patent) to Breed. The '701 patent discloses a sensor system for initiating deployment of an occupant protection apparatus in a vehicle, such as an air bag, to protect an occupant of the vehicle in a crash. A neural network is trained using data from approximately 25 crash events, and in addition, techniques of velocity and crash scaling are used to create a large library of crashes. A sensor senses deceleration of the vehicle, and the neural network determines if the signal contains a pattern characteristic of a vehicle crash by directly comparing the signal to the library of crash events. If the neural network determines the signal from the sensor is similar to a stored signal in the library of crash events, a deployment initiation mechanism initiates deployment of the occupant protection apparatus.
Although there are prior art systems for venting a refrigerant from an air conditioning system in anticipation of a leak, there remains the need for a system that more accurately predicts the possibility of a refrigerant leak from an air conditioning system of a vehicle during a crash.